Explosion proof industrial truck



March 28, 1961 F SCHRECK 2,976,945

AEXPLOSION PROOF INDUSTRIAL TRUCK Filed Oct. 23, 1958 5 Sheets-Sheet 1 /ZZ/ lvENToR Irvin E Schreck March 28, 1961 l. F. scHREcK 2,976,945

EXPLOSION PROOF INDUSTRIAL TRUCK Filed Oct. 23, 1958 5 Sheets-Sheet 2 March 28, 1961 1 F SCHRECK 2,976,945

EXPLOSION PROOF INDUSTRIAL TRUCK Filed Oct. 25, 1958 5 Sheets-Sheet 3 INVENTOR F1 5 Irvin ESchreck 87M?, am im ATTORNEYS March 28, 1961 l, F lSCHRECK 2,976,945

EXPLOSION PROOF INDUSTRIAL TRUCK Filed Oct. 25, 1958 5 Sheets-Sheet 4 INVENTOR Irvin I'. Schreck March 28, 1961 l. F, scHREcK EXPLOSION PROOF INDUSTRIAL TRUCK 5 Sheets-Sheet 5 Filed 0G13. 25, 1958 INVENTOR Irvin F. Schreck United States Patent O EXPLOSION PROOF INDUSTRIAL TRUCK Irvin F. Schreck, South Euclid, Ohio. The Moto rruc Co., 1953 E. 59th St., Cleveland 3, Ohio) Filed Oct. 23, 1958, Ser. No. 769,208

7 Claims. (Cl. 180-19) l,This invention relates to industrial trucks of the type that are provided with a propelling and steering unit that includes a traction Wheel and electric driving motor and that is mounted to turn about a vertical axis with respect to the truck body. Such trucks are powered by means of suitable current delivering means mounted on the truck body such as one or more storage batteries that are connected to the motor and its control switches to deliver electric current thereto.

The present invention relates particularly to a structure affording protection against explosions when trucks of the i character referred to are operated in an atmosphere containing combustible vapors or gases.

Trucks of the character referred to are designed to make short turns and the steering and propelling unit is usually so mounted in the truck body that it can be turned substantially 90 to the right or to the left from a straight ahead position and the conductors leading from the motor and controlling switches to the current delivering means on the truck body must permit such turning movements. Heat suicient to ignite a highly combustible vapor or gas may be generated by arcing between switch contacts or upon separation of a conductor from a terminal or upon rupture of a conductor, the breaking of the circuit causing arcing due to the passage of electric current through an air gap. Heating may also be caused by short circuits which may be caused by the Wearing Iaway of insulation on flexible conductors which are being continually exed and twisted due to turning movements of the steering and propelling unit.

To prevent explosions dueto any of the causes above mentioned the steering and ypropelling unit isprovided with an enclosure for the driving motor and control switches which is of sufficient strength to withstand explosion of gases within the housing and which is so constructed that combustion gases can escape from theinterior of the enclosure only through restricted passageswith heat`ab.

which are ofa length suicient to eifectivelycool any com` bustion gases created by ignition of vapor or gases within the housing before such gases reach 'the outside atmosphere.

`As lfurther protection against explosions, all'conductors extending from the motor housing to the truck body are titl enclosed in conduits extending from the housing on the l steering unit to aclosed compartment on the truck body where they areconnected to `current delivering means and, in order to protectconductors .against damage due to turning movements ofthe 'steering unit, the housing isv provided fwith A an upper. section; that 'is mounted on the lower motor enclosin'gsection'to 'turn' about a vertical axis ice with respect thereto, the upper section communicating with the lower section through a central opening. The conductor conduits extending to the truck body are connected to the upper section and the conductors connected to the motor and the motor control switches extend through the central opening. The conductor conduits connecting the housing on the steering unit with the truck body are preferably exible enough to permit the upper section to turn with the lower section when the steering unit is turned through small angles but causing the upper section to turn relative to the lower section when the steering unit is turned through large angles. To reduce the wear and tear on conductors due to continual turning movements of the steering unit, the upper housing section is preferablyprovided with fixed terminals to which the conductors extending into the housing from the conduits are attached and suitable exible conductors extend from these terminals through the central opening to the motor and switches mounted in iixed positions within the lower section of the housing.

In order to prevent an operator of the truck from obtaining access to conductors kor switches while the truck is being operated in an inflammable atmosphere, the main housing is provided with a closure that `requires special tools to operate it and the battery compartment on the truck body is provided with a key operated closure. The closure locking means also serves to lock the conductor conduit or conduits to the battery compartment and a safety switch or switches controlled by such locking means serves to break all control circuits leading from the battery compartment whenever the locking means is moved to releasing position, so that all circuits are dead whenever the locking means is released.

Objects of the invention are to provide an electrically operated industrial truck of the character described in Ywhich the conductor cables are protected against wear and breakage, to provide a truck in which all electrical connections which are capable of arcing or which might becomerheated to a temperature high enough to ignite combustible gases are lenclosed in a llame proof enclosure capable of withstanding explosions due to ignition of gases within it, to provide means for preventing unauthorized access to the battery, and to provide means for automatically deenergizing all circuits prior to disconnection of conductor cables from the source of current.

Reference should be had to the accompanying drawings in which:

Figure l is a side elevation of a truck embodying the invention;

Fig. 2 is a fragmentary top plan view of the forward portion of the truck showing the battery compartments and motor housings;

Fig. 3 is a fragmentary vertical section through the upper portion of the battery compartment taken on the line indicatedat 3 3 in Fig. -2 and showing the connec tion of the conductor conduit tothe compartment and the plug and socket connection between the conductors in the conductor conduits and the conductors within the battery compartment;

Fig. 4 is a vertical section takenlongitudinally of the truck through the steering and driving unit, with the unit in a straight ahead position, the section being taken von the line indicated at 4-4 in Fig. 2;

Fig. 5 is a vertical section through the steering and driving means taken at right angles to the section shown in Fig. 4 as indicated bythelineS-S in Fig. 2;

Fig. `6 is a fragmentary 'horizontal section through the lower portion o'f the main motor housing as indicated by the Vline 6-6 in Fig. 4; n

Fig. 7 is =a fragmentary vertical section through the base portion of lthe main motor housing, taken'on the line indicated at 7-7 in Fig. 6 and showing the main motor control switches;

Fig. 8 is a fragmentary horizontal section showing the main motor deenergizing switch that is controlled by the steering handle;

Fig'. 9 is a fragmentary ver-tical section taken on the line indicated at 9-9 in Fig. 2 and showing the means for locking the conductor conduits to the wall of the battery compartment;

Fig. 10 is a fragmentary section taken on the line indicated at 111-10 in Fig. 9 and showing one of the key locks and one of the safety switches that serves to deenergize all circuits before separation of the plug and socket connecting the external conductors to the battery leads; and

Fig. 1l is a wiring diagram showing one way in which storage batteries may be connected to the motorsl and control switches.

In the accompanying drawings the invention is shown applied to a truck of the lift fork type having a body 1 supported on rear wheels 2 and upon a front steering and propelling unit which has a traction wheel 3. As shown in Figs. 4 and 5 of the drawings, the traction wheel 3 is mounted on an axle 4 that is mounted in an annular bearing member or ring 5 that turns about a vertical axis in an annular bearing 6 fixed to the truck body 1. The traction wheel 3 is driven by an electric motor 7 supported on the ring 5 and 'a driving connection is provided between the wheel 3 and a motor 7 through a belt 8 running over pulleys 9 and 1t) mounted on the motor shaft and on a countershaft 11 beneath the motor, through a second countershaft 12 driven from the shaft 11 through reduction gears 13 and through a sprocket chain 14 running over a small sprocket 15 on the shaft 12 and over a large sprocket 16 that rotates with the wheel 3. The steering unit is turned by means of a steering handle 17 that is pivoted at its lower end to a bracket 18 fixed to the supporting ring 5. The handle 17 swings vertically and provides means for turning the steering unit to steer the truck. Y

The present invention is applicable to trucks designed for various purposes'but is illustrated as applied to a truck of the lift fork type which is provided at its rear end with a fork 19 that is mounted for vertical movement on a standard 2d. As is the usual practice, the fork is operated hy means of a suitable fluid pressure motor (not shown) to which fluid'is delivered through a valve 21 controlled by a lever 21a by means of `an electric pump Voperating motor 22.

A suitable compartment 25 is mounted on the truck hody 1 Vimmediately tothc rear of the steering' unit and suitable current delivering means such as one or more storage batteries is mounted within the compartment 23.

A sectional housing is provided on the steering unit that is composed of a lower section24 that encloses the motor 7 and an upper section ,24a that is mounted to turn upon a vertical axis with respect to the lower section 24. The sections 24 and 24a are coaxial with the supporting lring 5 and communicate with each other through a central opening. The lower section 24 is mounted on a base 25 that may be cast integrally with the ring 5 and which is disposed immediately over the traction wheel 3.

A gear housing 26 is mounted Aon the base 25 centrally thereof and an opening 27 is provided in the base 25 at one side of the housing 26. The sprocket 15 on the shaft 12 directly` overlies the open-ing 27 which provides a passage for the sprocket chain 14. A closure member 28 which maybe integral with'the base 25 engages with one side ofthe housing 26 and closes the opening 27. The base 25 is connected to the supporting ring 5 by means of integral legs 29 and 30-which are positioned over opposite 'ends ofthe aide 4. The supporting leg 30 is tubular in form and provides a housing for the chain 14 and sprocket 16, a cover plate 31 being provided at the lower end of the tubular ring to enclose the chain 14 and sprocket 16 below the axle 4. The shaft 11 projects through one wall of the housing 26 to support the pulley 10 within the housing section 24 but outside the housing 26. The shaft 12 projects through the opposite wall of the housing 26 and supports the sprocket 15 outside the housing. Any gases escaping from the housing 24 through the housing 26 must first pass through the bearing of the shaft 11 and then through the bearing of the shaft 12 and, since the metal of the housing is heat conductive, any combustion gases ignited within the housing 24 would be cooled below the danger point before escaping through the passages required for the drive shafts 11 and 12.

The base 25 is provided with an internally threaded upwardly projecting cylindrical flange 32 which receives the threaded lower end of a cylindrical wall 33 which forms the upright wall of the housing section 24. Th-e housing section 24 has a top .34 that is integral with the cylindrical wall 33 and this wall is provided with a central opening that is surrounded by a boss 35. A short pipe section 36 is secured by suitable means such as welding in the boss and is externally screw threaded. The upper section 24a has a cent-rally downwardly projecting boss 37 surrounding a central opening in its bottom 3S and this boss is internally threaded to screw onto the pipe 36. The screw threaded connection between the housing sections 24 and 24a permits the section 24a to turn with respect to the lower section 24. The screw threaded connection between the wall 33 and the base 25 and the screw threaded connection between the boss 37 and the pipe 36 provide restricted passages for escape of combustion gases under pressure and the metal forming the walls of such passages provides ample heat absorption to insure lowering of the tempera-ture to below ignition temperature before such gases pass into the surrounding atmosphere. The housing section 24a has a top wall 39 provided with a large circular opening that receives a circular screw threaded cover 40 that has a sealing flange 41 that engages the top wall 29 around the opening. The cover 40 is provided with wrench lugs 42 for engagement with a special wrench suitable for unscrewing the cover.

The section 24a is preferably rectangular lin horizontal cross section, having a front wall 43, a rear wall 44 and side walls 45 and 46. A terminal bar 48 is mounted within the housing section 24a adjacent the side wall 45 and a similar terminal bar 49 is mounted therein adjacent the opposite side wall 46.

One or more conductor conduits connect the upper section 24a to the compartment 23. As herein shown, two conductor conduits 50 and 51 which may be of identicalconstruction, connect opposite side walls 45 and 46 .of the housing section 24a to the compartment 23. As

Vthat is connected by a union 53 to an elbow 54 to which a vertically disposed flexible section 55 is attached. Each of the conduits isrprovided with a second vertical iiexible 'section 56 connected at its lower end to the lower end of the section 55 by a rigid horizontally disposed section 57. The upper ends of the flexible sections 56 are connected by elbows 58 to a short horizontal pipe section 57 which, las shown in Fig. 3, has telescopic t in a sleever60 mounted in the front wall 61 of the compartment 23. Each sleeve 60 is provided with a concentric socket 62 which receives a plug 63 attached to the conduit end section 59. The plug 63 and sockets 62 serve to electrically connect the conductors mounted within .the `compartment 23 with the conductors that extend throughrthe conduits 50 and 51. Locks are provided for securing the conduits 50 and 51 to the compartment 23. Each Vof the end sections 59 has a flanged collar 64 that is engaged byra locking plate 65. The conduits 50 and 51 are attached to the wall 61 adjacent opposite ends thereof and theflocking plates 65 are hinged to the free edge of the compartmentflid 66 so that when the plates 65 are secured in afposition' to lock the conduits against separation from the battery compartment, the lid 66 is also locked in closed position.

s shown in` Figs. 9 and 10, each plate 65 has a r1g1dly attached locking pin 67 that projects through an opening 68 in the front wall '61' when the locking plate isswung downto conduit engaging position. Each lock# ing pin 67 is provided with a notch 69 that receives the bolt 70 of a key operated lock 71 to retain the locking plates -in their locking positions. The combined conduit and lid lock serves to prevent unauthorized access to the compartment 23 and to prevent separation of the conduits from the compartment. Safety switches are also provided to insure deenergization of all external circuits before the plugs 63 are withdrawn from the sockets 62. As shown in Fig. l0, each locking pin 67 is provided with a'beveled end 72' that engages with a pin 73 to close the contacts ofl a' normally open safety switch 74 so that whenever the lock bolt 70 is' released and the lock plate 65 is swung to releasing position, the switches 74 are automatically opened so that all external circuits are opened and there will be no current owing through the plug 62`and socket 63 when they are pulled apart. This preventsignition of any combustible gases in the housings and conduit when-the battery compartment is opened in the repair Shop.

A directional switch assembly and a series-parallel speed control switch assembly 76 are mounted on the motor 7 within the housing section 24 and a control switch indicated generally at 77 is mounted within the housing section 24 on the base 25. The switch 77, as shown in Figs. 6 and 7, is provided with contacts 78, 79 and 80 secured to a horizontal supporting bar 81 and normally open-spring contact members 82, 83 vand 84 are engageable with the switch contacts .78, 79 vand 80, respectively. The contact members 82, 83 and 84 are in the form of spring bars each provided with a V-shaped ridge 85 and with a anged end 86 bolted to the supporting bar 81. The contacts 82, 83 and 84 are actuated by means of a horizontally sliding actuating member 87 that has reduced end portions 88 that slide in supporting posts 89 fixed to the base.V Springs 90 normally hold the actuating member 87 in a central neutral position. `The actuating member 87 has shoulders 91 and 92 that engage with the ridges 85 of thev movable'contact members 82 and 83 to move the contact 82 vinto engagement with the contact 78 upon movement of the member 87 to the right from the position shown in Fig. 7 and closing the contact member 83 when moved to the left from the position shown in Fig. 7. The member 87 is provided with intermediate shoulders 93 which move the central contact members 84 to closedposition upon movement of the actuating member 87 in either direction. Movement of the member 87 in one direction causes the motor 7 to be driven in a direction to propel the truck forwardly and movement in theopposite direction causes the motor .to be driven in a reverse direction.' The central contact 84 controls the' series-parallel switch 76 to move the same to its series position to start the motor slowly in either direction. Since the raised portions forming the shoulders 934 are short, ,they move past the ridge 85 of the Contact member 84 to permit the same to move to open position kto permit the switch 76 to move to its parallel position todrive the motor at a higher speed.

Therswitch actuating member 87 is operated by a control sleeve 94 at the outer end of the handle 17, the sleeve 94 being mounted onthe 'handgrip so that the operator can turn it in either direction to the extent desired. AsVr shown in Fig. 4, the sleeve 94 is connected to the switch operating member through a rod 95 extending from the outer end of the handle 17 to adjacent the pivotal connection of the handle to the bracket 18 Where it is connectedby apivot 96 to a bell-crank lever 97 that Vis pivoted at 98 to the brackety 18 and that has a pivot 99 connecting it to a horizontally movable rod 100 that is attached at its inner vend to an arm 101 fixed to the lower end of a vertical shaft 102 that extends vertically through the base 25 and that has a screw bearing in a boss 103 in the base. Within thehousing section 24 the shaft 102 has a horizontal arm 104 xed to its upper end and connected by a link 105 to one end of the actuating member' 87'. By turning the control sleeve 94 in one direction or the other the switch 77 may be operated to drive the motor and control the speed in either direction. The screw bearing of the shaft 102 provides an elongated restricted passage and the boss 103 provides a heat absorbing wall for the passage to cool any gases forced through the bearing.

Means is preferably provided for automatically deen ergizing the driving motor whenever the steering handle 17 is moved to vertical position. The motor circuit is opened by means of a normally closed switch 106 mounted on the base 25 that has a contact actuating pin 107 in the path ot a pin 108 slidably mounted in a boss 109 in the ange 32 of the base 25. The pin 108 is also guided by a bearing member 110 on the base 25 inwardly of the ange 32 and is normally held in retracted positionby means et a spring 111 interposed between the bearing member 110and a ilange 112 on the pin 108'which is normally held by the spring in engagement with the inner face of the boss 109. The pin 108 has a head 113 at its outer end that is in the path of the handle 17 and that is engaged by the handle as the handle approaches its vertical position. The elongated bearing provided by the boss 109 serves to cool any gases forced under pressure through the bearing in the boss 109.

A control switch 114 for the pump motor is mounted in the upper iousing section 24a and is operated by means of a handle 115 journaled in the front wall 43 of the housing section 24a. The handle 115 i'sattached to a screw threaded shaft 116 that has a threaded bearing in the wall 43 and inside the housing the shaft 116 has an actuating arm 117 attached thereto for closingv the v switch 114. The motor 22 isenclosed in a housing 119 and a conductor conduit 118 extends from the rear wall 44 of the housing section 24a to the motor housing 119. The conduit 118 includes a downwardly extending ilexible section 120 that is connected at its upper end through an elbow 121 to the housing section 24 and at its lower end to a rigid section 122 that extends past the underside of the battery compartment 23.

Fig. ll shows the general arrangement of controlling and operating circuits energized by electric storage batteries 123 and 124 mounted in the compartment 2.3. Leads from the battery 123 are connected to terminals on the bar 49 in the upper housing section 24a and leads from thebattery 124 are connected to terminals on the bar 48. The sockets 62 through which the -battery leads are connected to externalr circuits are indicated diagram.- ma-ticallyl and normally open switches 74 are shown adjacent the sockets 62 to interrupt all control circuits when the locking plates are moved out of engagement with the wall of the battery compartment;

The directional switch assembly 75 includes solenoids 125 and 126 that are energized by contacts S2 and 83 of the control switch .77 and that operate contacts F-l, F-2 and F-S and R1, R-Z and R3 of forward and reverse switches. The series-parallel switch assembly 76 includes a solenoid 127 that is energized by the contact 84 of the control switch 77 to shift the contacts 12S and 129-from their'l normal position shown in full lines in Fig. 1l. Contacts F-3 or R-S complete the circuit through the field 130 of the motor 7 and F-l and F-2 or R-1 or R-Z complete the circuit in opposite directions through the motor armature 131. In their lnormal posi tion the contacts 128 and 129 connect the batteries 123 and 124 in parallel to the armature 131 and when'tne solenoid 127 is energized the contacts 128 and 129 are moved out of their normal position to a position where the contact 128 connects the batteries in series to the armature 131 to start the motor at slow speed. When movedin one direction the slide 87 closes contact 82 to operate the forward switch F and when moved in the opposite direction closes the contact 82 to operate the reverse switch R. Upon initial movement in either direction, the solenoid 127 is energized to shift the contact 128 to its series position for starting the motor. Continued movement of the slide 87 moves the shoulder 93 engaging the contact 94 past the contact 94, allowing it to open, deenergizing the solenoid 127 and allowing the contacts 128 and 129 to move to the position shown in Fig. l1, where the armature 131 is connected in parallel to the batteries 123 and 124 to drive the motor at a higher speed. The control switch 114 in the upper housing section 24a controls a solenoid 132 that closes a normally open switch 133 to operate the pump motor 22.

It is to be understood that in accordance with the provisions of the patent statutes, variations and modifications of the specific devices herein shown and described may be made without departing from the spirit of the invention.

What I claim is:

l. An explosion proof industrial truck comprising a Wheel supported body, a steering and propelling unit mounted to turn about a vertical axis with respect to said body and including a traction wheeland an electric mortor, means for turning said unit to steer the truck, a flame proof housing of heat conductive material enclosing said motor, driving means connecting said motor to said wheel including a movable member extending to the exterior of the housing, means for controlling said motor comprising a switch in said housing and a movable switch actuating member extending from the exterior to the interior of said housing, means providing restricted passages with heat absorbing walls around said movable members for escape of combustion gases from said housing, a compartment in said truck body, current delivering means in said compartment, a flexible conduit connecting said housing to said compartment, means connecting said switch and said motor to said current delivering means, a conductor in said conduit, a conductor in said compartment and a plug and socket connection in a wall of said compartment between said conductors, means for locking said conduit to said compartment, and means controlled by said locking means for breaking the connection between said current delivering means and said conduit conductor independently of said plug and socket.

2. An explosion proof industrial truck comprising a body having rear supporting wheels, a steering and propelling unit supporting the front end of said body and mounted to turn with respect to said body about a vertical axis, said unit including a traction wheel and an electric motor, means for turning said unit to steer the truck, a flame proof housing forming an enclosure for said motor and having a bottom wall above said wheel, a gear box mounted on said base and having a side wall with an exterior face outside said enclosure and an opposite side with its exterior face within said enclosure, shafts extending through bearings in said side walls which are the only openings to the interior of said gear box, a driving connection from said motor to one of said shafts, gearing in said box connecting said shafts and a driving connection from the other of said shafts to said traction wheel outside said enclosure, a motor control switch in said housing, means for actuating said switch, a battery compartment on said body, a flexible conduit connected at one end to said compartment and at the other to said housing, and means for supplying current to said switch and said motor including con- ;ductors extending through said conduits.

3. An explosion proof industrial truck comprising a body having rear supporting wheels, a steering `and propelling unit supporting the front end of said body and mounted to turn with respect to said body about a vertical.` axis, said unit including a traction wheel and an t; electric motor, a llame proof housing formingv an enclosure for said motor and having a base forming the bottomwall thereof, means for turning said unit to steer the truck comprising a vertically swinging handle pivoted to said base, means including a movable member extending through a wall of said housing for driving said traction wheel from said motor, a motor control switch in said housing, a movable control member on said handle, an upright shaft extending through said base and journaled therein, means Within the enclosure connecting said shaft to said switch to actuate the same upon turning movement of said shaft and means outside the enclosure connecting said control member to said shaft to impart turning movements thereto, a battery compartment on said body, a llexible conduit connecting said compartment to said housing, and means including conductors extending through said conduit for supplying electric current to said switch and to said motor.

4. An explosion proof truck according to claim 3 in which the upright switch operating shaft is mounted to turn in a screw threaded bearing in said base.

5. An explosion proof industrial truck comprising a wheel supported body, a steering and propelling unit mounted vto turn about a vertical axis with respect to said body and including a traction wheel and an electric motor, means for turning said unit to steer the truck, a ame proof housing of heat conductive material enclosing said motor, said housing having a lower section in which said motor is mounted and an upper section opening to said lower section at said Vertical axis and mounted for turning movements with respect to said lower section about said vertical axis, means for driving said traction Wheel from said motor including a shaft extending through a wall of said lower section, means for controlling said motor comprising a switch Within said housing and a movable actuating member extending through a wall of said housing, bearings for said shaft and said actuating member and said upper and lower sections that provide restricted passages for escape of combustion gases from said housing, a closed compartment mounted on said body, a flexible conduit attached at one end to said upper section and at its other end to said compartment, said conduit being closed at the end connected to saidl compartment and opening to the interior of said upper section, an electric battery in said compartment, and means for connecting said battery to said switch and motor comprising terminals in said upper section, exible conductors connecting said terminals to said motor through said opening, llexible conductors connected to said terminals and extending through said conduit conductors within said compartment connected to said battery and a plug `and socket connection between the conductors in said conduit and the conductors in said compartment.

6. An explosion proof industrial truck comprising a body having rear supportingwheels, a steering and propelling unit supporting the front end of said body and mounted to turn with respect to said body about a vertical axis, said unit including a traction wheel and an electric motor, means for turning said unit to steer the truck, a dame proof housing enclosing said motor, said housing comprising a lower section containing said motor and an upper section mounted on the lower section to turn with respect thereto about said vertical axis and communicating therewith through an axial opening, a motor control switch in said housing, means providing a driving connection from said motor to said traction wheel including a rotatable driven member extending through a wallA of said lower section, means for operating said switch including a movable actuating member extending lthrough a wall of said housing, means forming restricted passages with heat absorbing walls surrounding said movable members for escape of combustion gases from the interior of said housing, a battery compartment on said body, two conduits connecting said upper section to said compartmentLsaid conduits; being attached to and opening into opposite sides of said upper section and at laterally spaced points to said compartment and being closed at the ends connected to said compartment, an electric battery in said compartment, and means for supplying current to said switch and said motor comprising terminals within said upper section, exible conductors attached to said terminals `and extending through said axial opening to said switch and said motor, exible conductors connected to said terminals and extending through said conduits to the closed ends thereof, conducto-rs in said compartment connected to said battery and means connecting the conductors Within the compartment to the conductors in said conduits.

7. An explosion proof industrial truck according to claim 6 in which the conductors Within the battery compartrnent and the conductors in said conduits are connected by plug and so-cket connections, in which means is provided for locking the plugs and sockets against References Cited in the le of this patent UNITED STATES PATENTS 1,228,577 McElroy June 5, 1917 2,076,261 Bauroth Apr. 6, 1937 2,159,087 Ieirey May 23, 1939 2,299,206 Berg Oct. 20, 1942 2,368,492 Ralston Jan. 30, 1945 2,395,323 Framhein Feb. 19, 1946 2,478,327 Schreck Aug. 9, 1949 2,592,091 Weaver Apr. 8, 1952 2,736,826 Hoover Feb. 28, 1956 

